Lubricant for metal working

ABSTRACT

THE PRESENT INVENTION PROVIDES A SUPERIOR METAL ROLLING LUBRICANT COMPOSITION USEFUL AS A PRE-COATING OIL AND AS A COATING IN ROLLING OPERATIONS COMPRISING A MINERAL OIL, A FATTY ACID OR THE POLYMERS OR GLYCERIDES THEREOF, AND A WAX, PREFERABLY A PARAFFIN WAX SUCH AS SLACK WAX. THE COMPOSITION MAY ALSO CONTAIN A SULFURIZED MINERAL OIL, OR FATS, OR OTHER SULFUR-CONTAINING COMPOUNDS, AS WELL AS ORGANIC PHOSPHATES OR PHOSPHITES TO PROVIDE INCREASED PROTECTION TO THE METAL SURFACE DURING COILING AND UNCOILING. THE LUBRICANT COMPOSITION PROVIDED IS PARTICULARLY USEFUL IN THE COLD ROLLING OF STEEL.

3,0003% Patented Aug. 17, 1971 3,600,310 LUBRICANT FOR METAL WORKENGAlan R. Eyres and Jacques C. Dillon-Corneck, Mullica Hill, NJ, assignorsto Mobil Oil Corporation, New York, NY.

No Drawing. Filed Mar. 20, 1969, Ser. No. 808,987 Claims priority,application Great Britain, Jan. 10, 1969, 1,673/69 lint. Cl. Clllm 1/38,3/04, 5/10 US. Cl. 252--48.6 11 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION Field of the invention The invention isconcerned with compositions useful in treating metal surfaces,particularly ferrous metals. It is especially concerned with oilcompositions useful as coatings for protection of metal surfaces duringstorage and as lubricants during steel cold rolling operations.

As cold rolling lubricants, the compositions of this invention reducegouging and scratching of the metal surfaces during cold rolling. Theyalso are effective in providing clean surfaces following heat treatment,as in annealing processes. This latter property is believed to be due inpart to any residual oil being burned off during annealing. The majorfactor, however, is the ability of the composition to effectively floatmetal fines, tamp oil and diet present in the emulsions used with theinventive compositions, thus eliminating the possibility of these beingdeposited on the rolled metal to contribute to discoloration afterannealing.

Description of the prior art Various types of lubricant compositionshave been used in metal working, as for example in cold rollingprocesses involving ferrous metals. For the most part, however, suchcompositions provide inadequate lubrication or cause objectionablesurface discoloration or imperfections. In many instances, they areineffective in preventing the formation of rust during processing.

The art has made several attempts to overcome the deficiencies ofpresently used lubricants. One such attempt is outlined in U.S. Pat. No.3,298,954, which is directed to compositions containing polybutenes,fatty acids, and in some cases, sperm oil wax. US. 3,071,544 describesan emulsifiable oil which, in addition to its other stated advantages,is alleged to have the ability to provide a clean metal strip uponannealing of the metal after the rolling operation. Such oil comprisesan emulsifier, a mineral lubricating oil, an alkali metal oralkanol-amine salt of petroleum sulfonic acids, an organicmonocarboxylic acid, as for examples oleic and stearic, or an alkanolester thereof, and an alkanolamine. The acid or the alkanolamine may bein slight excess.

It is not believed, however, that either of the justmentioned patents,or any art known, discloses the compositions of this invention, andparticularly the advantages which are derived from their use.

It will be noted from the above art that mineral oilbased lubricantshave been used almost exclusively in cold rolling steel, but sufferedthe disabilities mentioned in the first paragraph under this section,namely, inadequate lubrication and the forming of objectionablediscoloration on the metal surface and the inability to prevent depositsupon annealing. The patentee in U.S. Pat. No. 3,071,544, in his attemptto overcome certain of these deficiencies, compounded a complex mixtureof materials for use as an emulsion. In the second patent mentioned, US.3,298,954, patentee used polybutencs as a substitute for mineral oils ashis solution to the problems inherent in the use of mineral oil. Whileboth of these compositions are no doubt effective for their intendedpurposes, they do have among others, the disadvantage of relativelyhigher cost.

While it is true that the requirements for metal working lubricants haverecently become more stringent because of new alloys, demands for higherproduction rates, and the like, it is also true that the metal workingindustry is seeking improved lubricants which are economical for use inits operations. The composition of this invention has that advantage.Basically, the discovery herein is that the inexpensive mineral oil basecan be used in a com position which overcomes the disadvantages of priorart mineral oil-based lubricants, when such lubricant contains anaturally occurring wax such as slack wax. The advantages of such acomposition will become apparent from the remainder of this disclosure.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided a lubricant composition comprising a liquid lubricant,especially a mineral lubricating oil, an acid or acid dervativesselected from the group consisting of an aliphatic monocarboxylic acidhaving from about 12 to about 26 carbon atoms, a polymer or a glyceridethereof and a wax, preferably a paraffin wax such as slack wax, whichcomposition may have additionally present therein an agent for impartingadditional load carrying properties thereto.

The composition is especially useful as a precoating for steel toprevent corrosion thereof during storage before rolling, to providelubrication during coiling and uncoiling processes to prevent surfacescratching and gouging, to provide lubrication during rolling in thefirst pass of a reversing mill or first stand of a tandem mill and tomaintain the circulated mill coolant in a clear condition by floatingfines, tamp oil and dirt to the surface in the reservoir of thecirculation system.

DESCRIPTION OF SPECIFIC EMBODIMENTS The liquid lubricants used in thisinvention include naphthenic and paraffinic mineral oils having akinematic viscosity in the range of from about. through about 350 S.U.S.at 100 F., as well as synthetic lubricants such as synthetic esterlubricants and alkylene oxide-derived fluids. This liquid lubricant ispresent in the amounts ranging from about 50% to about 90% by weight ofthe neat composition, and preferably from about 60% to about by weight.

From about 1% to about 10% by weight of the composition is an aliphaticmonocarboxylic acid having from about 12 to about 26 carbon atoms or apolymer or glyceride thereof. This range includes lauric, myristic,palmitic and stearic acids, which are normally solid at room temperatureand normally insoluble in mineral oils and water. Preferably thesaturated acids are employed, and the more preferred one is hydrogenatedtallow fatty acid. Also included are other designated fatty acids suchas soya bean fatty acid. No great problems have been encountered, norare any contemplated which cannot be overcome in their use since atelevated mixing temperatures and at mill operating conditions theseacids, polymers and glycerides may become liquified and miscible withthe mineral oil, while at low temperatures the paraffin wax presentsolidifies and maintains the solid fat in a stable suspension. Forapplication to the metal surface, the composition must be heated to sucha temperature that the wax/oil/fat mixture becomes liquified to ensure auniform coating on the metal surface; under these conditions ahomogeneous mixture is maintained.

The lubricant composition contains from about to about 15% by weight ofa wax, such as slack wax, i.e., a. light neutral wax obtained bydewaxing the oil fraction to crystallize the higher melting hydrocarbonspresent therein and pressing, filtering or centrifuging to separate theoil fraction. An example of such a wax is one containing about oil,having a M.P. of 50 C., and having a viscosity of 38.5 S.U.S. at 210 F.In the lubricant composition of the present invention, this so-calledslack wax is the preferred wax. Useful compositions may be achieved byusing a lesser quantity of another wax, such as beeswax or anotherparaffin wax, of similar molecular weight distribution, although such acomposition may be more expensive. At the present time, it is believedthat waxes of higher molecular weights may give rise to annealingproblems due to the inability to remove them prior to annealingoperations.

The lubricant composition may also contain from about 0.5% to about 25%by weight of an agent for imparting load carrying characteristicsthereto. Preferably a sulfurized mineral oil, such as a solvent refined150 S.U.S. 100 F. paraffin oil containing about 0.6% by Weight ofdissolved sulfur. Such load carrying (or E.P.) agents are well known tothe art. However, it may be mentioned that other sulfurized fats andoils, as well as many other sulfur-containing compounds may be used. Inaddition, phosphates and phosphites, such as his (nonylphenyl)phosphite, are also useful.

The function of a load carrying, or E.P., agent is to provide increasedprotection against gouging and scratching in the processing of metals,as in coiling and uncoiling operations. In rolling processes, this hasonly comparatively recently become a problem, since heretofore theweight of the metal coils was not suflicient to introduce appreciablemetal to metal contact with currently used precoat lubricants.

However, with the advent of larger and more powerful equipment forhandling metal coils, large coil weights are becoming more common. Withsuch high weights, lubricant compositions used in metal rollingoperations must protect the metal surfaces from scratching and gouging,and the inventive compositions serve to reduce both.

Having discussed the invention in general terms, the following will showhow the lubricants are prepared and utilized.

Lubricant compositions were prepared using the following substances:

Parts by weight Mineral oil 81 Hydrogenated tallow fatty acids 4 SlackWax Mineral oil 61 Hydrogenated tallow fatty acids 4 Slack wax l5Sulfurized mineral oil The mineral oil is a naphthenic oil having aviscosity of 300 S.U.S. at 100 F.

The hydrogenated tallow fatty acid is a commercial grade tallow acidcontaining from 1 to 3% myristic acid, 23 to 33% palmitic acid and 65 to77% stearic acid.

Number Weight Acid of carbons percent M yristic l4 3. 0 Palmitic- 16 23.l Palmitoleic. l6 3. 0 Stearie l8 l8. 1 ()leie 18 38. 0 Linoleic 18 4. 5

Unidentified l0. 3

Total 100. 0

The final composition had the following approximate analysis:

(III) Parts by volume Mineral oil Fatty matter 15 A commerciallyavailable emulsion was used in connection with the cold rollingoperations of Examples 3 and 4. This emulsion is constitutedsubstantially as follows: 97-98% water and 23% of a compositioncomprising 70% of a mineral and 30% of a fatty material containing anamine as emulsifier plus a small amount of non-ionic emulsifier. Theneat composition has a viscosity of 51 cs. at 100 F. and asaponification number of 60.

The substances comprising the composition of this invention may be mixedin any convenient order. Since the product is normally a solid atambient temperatures, adequate mixing may be accomplished by applyingheat to the mixing chamber. A temperature just above the melting pointof the highest melting component is sufficient for this purpose.

EXAMPLE 1 Comparative anti-rust properties Two tests were used. One wasthe standard Salt Spray test; the other was the so-called QCT Cabinettest.

Salt Spray Test.Steel test panels were coated with the variouscompositions and were hung in a spray cabinet maintained at F. and thepanels were sprayed With a 3% aqueous sodium chloride solution for 5minutes in each hour for the duration of the test. Times given in thetable below indicate interval before first rust spot appeared.

QCT Cabinet Test.A cabinet is constructed so that the base and sidesmake up the reservoir for the water and the roof is made up from thevarious test panels. In this test, water was placed in the reservoir ortank and was heated to F. Steel panels were coated on one side and werehung to form a roof over the tank. In this manner, water was allowed tocondense on the treated side. The results in the following table showthe times required for the first rust spots to appear.

From the above data, it is evident that it requires a longer time forrust spots to appear in either the QCT Ca'binet Test or in the saltspray test when using Composition I and II. The results obtained in theCabinet Test 6 show significant improvements with these twocomposicleanliness of the annealed strip was rated as medium tionscompared to Composition III. The Salt Spray Test, or normal, i.e., thescotch tape had picked up very few however, indicates an even moresignificant suppression particles. Three days following the substitutionof Comof corrosion, in that rusting is suppressed for from aboutposition -I, the cleanliness of the annealed strip was rated 3 to about6 times longer than when using Composition 5 as excellent, the scotchtape being virtually free of ad- III. hering particles.

EXAMPLE 2 Following the end of the test with Composition I, CompositionIII was again used as the coating. After two days, the annealed stripwas again as dirty as it had been The test used was the well-known4-Ball Test. The 10 t th t t f th t t with Composition III, followingresults were obtained by running the test for Comparative E.P.proper-ties 1 minute at 1800 r.p.m. EXAMPLE 4 SCAR DIAMETER AND WELDComparative flotation effectiveness Composition The cleanliness shown bythe use of Composition I i attributable, in large measure, to itsability to aid in floating the fine particles of metal, impurities andthe like present in the emulsion. This allows easy removal of suchparticles, as by skimming or decanting. In this way, it is possible toremove from the emulsion those foreign substances which tend to adhereto the metal and which as a The result? 9 thls example estahhsh lifi ofluhn' consequence produce dirty surfacesiii subsequent processcantcompositions exemplified by Composition II as ing of the metaL havingE.P. properties. Composition I, which contains AS is Shown by the f ll idata Compared to c th Sa Substances a8 COmPOSIhOII II except theposition III (first day), Composition I (last day) provides SlllfllriledOil, s no appreciable P p Since skimming material having higher ironcontent and allows welding occurred at the lowest 100 kg. load.Composition lower i Content in emulsion, in Spite of the i 1H fails at200 kg., and Composition II does not fail crease in the emulsionstrength over the period of the until the load reaches 250 kg. test.

ANALYSIS OF THE CONVENTIONAL EMULSION First day of trial using Coni-Last day of trial using Composition III as coating position I as coatingSkirnming materials Emulsion skimming materials Emulsion glen content,p.p.m 3 8 6, 200 no Emhis idns tihgth;h h '2 I:II IIIIIIIIIIIII On thefirst day of the trial Composition III was bein EXAMPLE 3 r a e0 used;Composition I was in use on the last (third) day of Comparativecleanliness of annealed strips the trial l h the product may be appliedto the Surface The results established the fact that Composition I is ofthe metal in any convenient way, as by brushing and a Superior hofatlmlag nt. the like, it is preferable in large scale treatment to use a sofar h 15 known, Q other D -Coat oil is also useful circulating System aswas done in this embodiment as a flota tion agent. While the combinationof acid and The lubricant compositions (Compositions I and III) Whrhlheral 0111s h hf essehtlal for g Q h i were applied to a low carbonSteel Strip having a thick it is believed that the ingredient mostresponsible is the ness of from 1.8 to 5 min. by means of a circulatingIt 15 known that temperature P y nd po taht system consistingessentially of a reservoir heated by role, both 111 the P P h 0 eomposition and in electrical resistance to a temperature of between Rthe temperature of the emulsion used in rolling operations.

and 1140 F, a pump lines ,(heated the Same With regard to thetemperature of preparation, it must perature) for dripping the producton both sides of the be Sufficlenfly hlgh to melt the acld, Its Polymerglyc ship, a Steel roll for distribution and a return line for eride sothis ingredient can become distributed uniformly returning the excess tothe reservoir. throughout the blend. Obviously then, the temperature Themetal strip was passed from 3 to 5 times, accorddunng preparafloh f theo position rnust he at least ing to Width, through a production scaleSingle above the melting points of the acid or acid derivative and stand4-high reversing mill at a maximum speed of about the W In the blehd' ha homogeneous mlxthre 650 mjmim The final thickness was 03 to 25 mm Asobtained, wait and/or acid will tend to separate, thus in previouslyindicated, a conventional emulsion at a temefiect destroymg the fiotahohProperhes of the Comphsl perature of 113 F. Was used.

The coils were annealed in a cracked gas (i.e., a mix- 60 Pnor artcoatmgs contammg no emulslfiers when I h d one 11 O to 95 h Washed oil?the metal strip by an emulsion, tend to float $22 i fg agg s ssiz g g at3 30 to the surface of the emulsion, but do not carry with them (8000C), and, after annealing, the cleanliness of the a significant amount offines, or not enough to prevent dirty surfaces upon annealing of themetal. The inventive compositions are also washed oif the surfacesduring rolling operations and they float to the surface of saidemulsion. In contrast, however, most of the fines are carstrip wasdetermined on a skin pass mill using the scotch tape method. In thismethod, a piece of scotch tape is applied to the strip surface andtransferred to clean white paper to provide a permanent record of theamount of loose dirt adhering to, the Strip Surface ried along, andthese can be easily skimmed or decanted, The initial strip was obtainedfrom. coils which had thus phevehhhg hh h h metal ShrfaCebeen coatedwith Composition III. After annealing and The lhvehhve ComposlhonsContalmhg Wax and held passing through the skin pass mill, the coil wasdirty, as its derivatives, and which y also Contain a load indicated bythe many particles adhering to the scotch carry g agent, work Well asflotation agents at u si n tape temperatures used for best results inmetal rolling. Gen- Subsequent strips were obtained following achangeerally, the lower end of the temperature range is between over toComposition I. On the first days operation, the about F. and F. Also,such temperatures usual- 7 1y range up to 140 F. to 150 F., but thepreferred temperature is between about 110 F. and 120 F. Thecompositions of this invention are operative as flotation agents withinthis range so long as there is a sufiicient amount of the compositionpresent in the emulsion to cause flotation of the fines.

Taken as a whole, the above tests involving the compositions of thisinvention show that the inventive lubricants are indeed exceptional.They are compounded of simple and readily available materials, thusproviding inexpensive lubricants to the art. Depending upon thecomposition selected, they provide (1) greater protection againstrusting of metal surfaces, (2) lubricants having good E.P. properties,(3) metal surfaces which are clean and clear of foreign matter, and (4)compositions which are excellent floating agents for fines which arepresent in the emulsions used in metal rolling. All in all, the resultsshow the discovery of compositions which could not have been discernedfrom the presently known art.

What is claimed is:

1. A lubricant composition comprising (a) at least 50% of a minerallubricating oil; (b) about 1 to of an aliphatic monocarboxylic acidhaving from about 12 to about 26 carbon atoms or a derivative thereofselected from the group consisting of polymers and glycerides; and (c)about 5 to 15% of a wax selected from the group consisting of paraflinwax and beeswax.

2. The composition of claim 1 which has therein an agent for impartingload carrying properties thereto.

3. The composition of claim 1 wherein said wax is slack wax.

4. The composition as defined in claim 1 wherein the acid derivative ishydrogenated tallow fatty acid.

, 5. The composition as defined in claim 1 wherein the wax is parafiinwax.

6. The composition of claim 1 wherein said lubricating oil is present inan amount of from about to about by weight.

7. The composition of claim 6 which has therein from about 0.5% to about25% by weight of an agent for imparting load carrying propertiesthereto.

8. The composition of claim 7 wherein the said agent is a sulfurizedmineral oil.

9. The composition as defined in claim 7 wherein the acid derivative ishydrogenated tallow fatty acid,

10. The composition as defined in claim 7 wherein the wax is paraffinwax.

11. The composition as defined in claim 7 wherein the wax is slack wax.

References Cited UNITED STATES PATENTS 2,126,128 8/1938 Montgomery 252562,167,439 7/1939 Kaufman 252-48.6 2,206,152 7/1940 Bennett 260-402.53,031,749 5/ 1962 Adams 252-49.5 3,298,954 1/1967 Brown 252-59 DANIEL E.WYMAN, Primary Examiner W. H. CANNON, Assistant Examiner U.S. Cl. X.R.252-495, 56

